Abstract: Robustness is one of the most basic requirements for invisible image watermark,Embedding strength and embedding location all affect robustness of watermark. In this paper, a new watermark algorithm for color images based on DWT is proposed. Making use of masking peculiarity of human visual system, the watermark image is adaptive embedded into the blocked lowest approximation components of blue components of color image on repeat embedding technology while most of other DWT methods embed watermark into the middle or high frequency components,so the embedding strength is greater .Moreover, two extraction methods can be used to enhance cropping attack and need not origin host image while only one extraction method is used. Experimental results show that the proposed algorithm keeps the quality of the image well and is robust enough to JPEG compression、noise 、 filtering 、image scaling、image enhancement、 mosaic and cropping etc.

摘要： 稳健性是图像隐藏水印最基本的要求之一，而水印的嵌入强度、嵌入位置影响水印的稳健性。本文提出了一种基于小波变换的彩色图像数字水印方案。利用了人眼视觉的掩蔽特性，在彩色图像的蓝色分量小波域的最低层逼近系数分块矩阵中，采用重复嵌入技术自适应地嵌入水印，水印嵌入强度较大，而现有的基于小波变换的算法大多将水印嵌入在各个方向的中频或高频中。水印提取时采用两种方案，从而使该算法的抗剪切能力很强，且提取水印时不需要原始载体图像，而现有水印系统的提取方案是唯一的。实验结果表明该水印系统不仅较好地保持了图像的质量，对JPEG压缩、噪声污染、滤波、缩放、图像锐化、马赛克效应、剪切和联合攻击等图像操作都显示了较强的鲁棒性。